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As the primary facility for crude oil storage, storage tanks play a critical role in achieving high operational efficiency and low energy consumption through comprehensive understanding of complex thermal convection mechanisms. This study establishes a theoretical model for the coil-agitator synergistic heating process in crude oil storage tanks, characterizing the coupled heat transfer between natural and forced convection. Dimensionless parameters including Reynolds number, Grashof number, and Richardson number are employed to quantitatively delineate the agitator-induced forced convection zone, crude oil natural convection zone, and mixed convection region. Based on the spatial distribution characteristics of multi-scale turbulent vortex structures within these zones, the interaction mechanisms between natural and forced convection are qualitatively analyzed, while the Richardson number is used to quantitatively characterize the primary influencing factors of vortex flow in each convection region. The results indicate that the tank's heat transfer is dominated by coil-induced natural convection with supplementary agitator-driven forced convection. A 2.45 m² forced convection zone forms near the agitator. Reduced agitator rotation angle generates high-speed vortex flow along tank walls, forming large-scale vortex structures with enhanced intensity. This expands the forced convection zone by 55% and mixed convection zone by 73%, prolonging forced convection trajectories while improving natural convection heat exchange, albeit causing localized non-uniformity. Multi-scale analysis reveals that in the natural convection zone, large vortices (≥34.08 m) govern energy transport via macroscopic convection, while small-scale vortices (≤11.99 m) facilitate energy conversion through viscous dissipation. In forced convection regions, 30° agitator rotation optimally develops large vortices (≥8.52 m), enhancing vortex intensity while reducing energy dissipation. Furthermore, Richardson number analysis shows that large vortices (Ri ∈ [0, 10]) in the forced convection zone primarily enhance convective heat transfer, whereas small-scale turbulent vortices (Ri ∈ [0, 1]) contribute to mixing and heat transfer through localized energy dissipation.

Predicting human thermal comfort and safety requires quantitative knowledge of the convective heat transfer between the body and its surrounding. So far, convective heat transfer coefficient correlations have been based only upon measurements or simulations of the average body shape of an adult. To address this knowledge gap, here we quantify the impact of adult human body shape on forced convection. To do this, we generated fifty three-dimensional human body meshes covering 1st to 99th percentile variation in height and body mass index (BMI) of the USA adult population. We developed a coupled turbulent flow and convective heat transfer simulation and benchmarked it in the 0.5 to 2.5 m·s−1 air speed range against prior literature. We computed the overall heat transfer coefficients, hoverall, for the manikins for representative airflow with 2 m·s−1 uniform speed and 5% turbulence intensity. We found that hoverall varied only between 19.9 and 23.2 W·m−2 K−1. Within this small range, the height of the manikins had negligible impact while an increase in the BMI led to a nearly linear decrease of the hoverall. Evaluation of the local coefficients revealed that those also nearly linearly decreased with BMI, which correlated to an inversely proportional local area (i.e., cross-sectional dimension) increase. Since even the most considerable difference that exists between 1st and 99th percentile BMI manikins is less than 15% of hoverall of the average manikin, it can be concluded that the impact of the human body shape on the convective heat transfer is minor.

Groundwater temperature and age are crucial proxy data that play a fundamental role in understanding regional-scale groundwater flow systems and managing drinking and geothermal water resources. To investigate groundwater flow as well as heat and age mass transport processes in a complex hydrogeological system with deep carbonate sequences and adjoining sedimentary basins (DCSBs), numerical simulations were carried out in two-dimensional synthetic and two- and three-dimensional field-based conceptual environments. The simulations carried out for the Buda Thermal Karst (BTK), Hungary, revealed that the increasing asymmetry in the water table and the appearance of DCSB-type heterogeneity could affect the transition from advection-dominated to conduction- and diffusion-controlled transport processes in the models. However, simultaneously, both effects significantly influence the intensity of groundwater flow. Thermal buoyancy was superimposed on the water table-controlled forced convection (mixed convection), causing significant age mass accumulations in the closed convection cells. To quantify and track the changes in physical processes in the DCSB-type system, the simultaneous use of monitoring parameters calculated in the different parts of the model domain (e.g., unconfined vs confined), contours of groundwater age and temperature, and histograms of normalized groundwater age are presented. The numerical results from the preliminary three-dimensional model were compared to the 14 C observation data in the BTK. The groundwater age calculated in the model was of the same order of magnitude as the results of 14 C dating from samples taken at different depths in the unconfined and confined parts, and from the deeper mixing zone of the BTK.

In the present paper, along with experimental study, CFD analysis of forced convection in a twisted tube is performed, using the transition SST model which can predict the change of flow regime from laminar through transition to turbulent. The differential governing equations are discretized by the finite volume method. The investigations are conducted for Reynolds numbers ranging from 100 to 50000 covering laminar, transitional and turbulent regimes, and for three length and three pitch ratios. The predictions are observed to show a good agreement with the measurements and published correlations of other authors. The analysis indicates that the large length ratio and small pitch ratio yields a higher heat transfer rate with relatively low performance penalty. The transition from laminar to turbulent regime is observed between Reynolds numbers of 2500 to 3500 for all cases. For almost all investigated cases the performance factors are greater than unity. nema

Forced convection heat transfer of multi-wall carbon nanotubes–iron oxide nanoparticles/water hybrid nanofluid (MWCNT–Fe 3 O 4 /water hybrid nanofluid) inside a partially heated τ-shaped channel has been numerically investigated. The effect of magnetic field is taken into account. The governing equations are solved by the lattice Boltzmann method in the domain, and the results were compared with other numerical methods by an excellent agreement between them. The effects of parameters such as Hartmann number (0 ≤  Ha  ≤ 60), volume fraction of nanoparticles (0 ≤  ϕ  ≤ 0.003) and different location of two heaters on the fluid flow and heat transfer are studied. The results indicate that for all cases, the average Nusselt number of each heater increases as the volume fraction of nanoparticles increases. The heat transfer characteristics were significantly affected by the arrangement of the two heaters. The heaters located on the left half of the top wall is convection-dominant mechanism, and the conduction heat transfer is the primary mechanism when the heater is on the right half of the top wall. The average Nusselt number increases as Ha increases for the heater of dominating convection mechanism but decreases for the heater of dominating conduction mechanism.

Solar energy is a ubiquitous renewable resource for photovoltaic (PV) power generation; however, higher operating temperatures significantly reduce the efficiency of PV modules, impacting their electrical output and increasing the levelized cost of energy (LCOE). This study aims to enhance conventional PV systems’ electrical efficiency and annual energy recovery while reducing the LCOE through thermal management using microchannel heat sinks (MCHSs) under forced convection. A 600 W monocrystalline PV module was analyzed, recognizing an efficiency reduction of ~20% under actual operating conditions due to thermal effects, with the surface temperature reaching up to 63.76°C without cooling. In addition, analytical calculations were used to determine an incident solar irradiance of 957.33 W/m 2 for an industrial location in Lahore, Pakistan. Similarly, computational fluid dynamics (CFDs) simulations were conducted using single and dual‐layer MCHSs configurations with water as the coolant at inlet velocities ranging from 0.01 to 1.0 m/s. The dual‐layer MCHSs significantly reduced the PV module’s surface temperature from 63.76 to ~25.65°C at an inlet velocity of 1.0 m/s, achieving a temperature reduction of 38.11°C. This thermal management increased the electrical efficiency from 18.33% (without cooling) to 22.27%, an efficiency gain of ~4%. The annual energy recovery improved substantially; at 1.0 m/s, the dual‐layer configuration increased the annual energy output by 227,954 kWh/year (about 21.89%) compared to the no‐cooling scenario, reaching 1,269,131 kWh/year. Furthermore, the LCOE was reduced to as low as 6.27 PKR/kWh over a 30‐year operational lifespan at lower velocities, demonstrating improved cost‐effectiveness. Meanwhile, optimal velocity was identified between 0.2 and 0.5 m/s, balancing thermal performance and economic viability. Finally, this study concludes that thermal management using dual‐layer MCHSs effectively enhances PV module efficiency, increases annual energy recovery, and reduces LCOE, contributing to sustainable and economical solar energy integration in industrial applications.

A local thermal non-equilibrium analysis of heat and fluid flow in a channel fully filled with aluminum foam is performed for three cases: (a) pore density of 5 PPI (pore per inch), (b) pore density of 40 PPI, and (c) two different layers of 5 and 40 PPI. The dimensionless forms of fully developed heat and fluid flow equations for the fluid phase and heat conduction equation for the solid phase are solved analytically. The effects of interfacial heat transfer coefficient and thermal dispersion conductivity are considered. Analytical expressions for temperature profile of solid and fluid phases, and also the channel Nusselt number (NuH) are obtained. The obtained results are discussed in terms of the channel-based Reynolds number (ReH) changing from 10 to 2000, and thickness ratio between the channel height and sublayers. The Nusselt number of the channel with 40 PPI is always greater than that of the 5 PPI channel. It is also greater than the channel with two-layer aluminum foams until a specific Reynolds number then the Nusselt number of the channel with two-layer aluminum foams becomes greater than the uniform channels due to the higher velocity in the outer region and considerable increase in thermal dispersion.

In this paper, vortex-induced vibration of a circular cylinder with forced convection heat transfer and entropy generation in pulsating alumina–water nanofluid flow is investigated numerically. Numerical simulation is carried out for a constant mass ratio of 2 and damping ratio of 0.01 at a fixed Reynolds number of 150. The ranges of reduced velocity, particle volume fraction and inlet velocity oscillation amplitude are 3–8, 0–5% and 0–1, respectively. It was found that the lock-in phenomenon, nanofluid concentration and inlet velocity oscillation amplitude have an effective role in increasing heat transfer and decreasing entropy generation. Two wake patterns (2S and 2P) were observed in the present simulation. For velocity oscillation amplitude of 1, the transition from 2S to 2P modes occurs in vortex shedding pattern.

In this work, flow boiling heat transfer coefficients of deionized water and copper oxide water-based nanofluids at different operating conditions have been experimentally measured and compared. The liquid flowed in an annular space. According to the experiments, two distinguished heat transfer regions with two different mechanisms can be seen namely forced convective and nucleate boiling regions. Results demonstrated that with increasing the applied heat flux, flow boiling heat transfer coefficient increases for both of test fluids at both heat transfer regions. In addition to, by increasing the flow rate of fluid, the heat transfer coefficient dramatically increases at both regions. Influence of inlet temperature of fluid to the annulus as a complicated parameter has been investigated and briefly discussed. Results showed that inlet temperature of fluid displaces the boundary between forced convection and nucleate boiling areas such that with increasing the inlet temperature, nucleation mechanism become dominant mechanism at lower heat fluxes. Furthermore, higher heat transfer coefficient can be obtained due to interactions of bubbles and local agitations. Also, Chen type model was modified in terms of thermo-physical properties and examined to experimental data. Results showed that experimental data are in a good agreement with those of obtained by the correlation with deviation up to 30%.

In this work, the thermodynamic performance of a forced convection solar air heater (FCSAH) was evaluated using two different absorber plate configurations, namely a flat absorber plate and a pin–fin absorber plate packed with latent heat storage material (paraffin wax). The experiments were carried out under the meteorological conditions of Coimbatore city in India. The parameters such as outlet air temperature, thermo-hydraulic efficiency and exergy efficiency were evaluated with reference to solar intensity, ambient temperature and ambient wind velocity. An artificial neural network (ANN) model was developed to simulate the thermodynamic performance of a FCSAH using flat absorber plate and pin–fin absorber plate packed with paraffin wax to have a realistic performance comparison. The ANN-predicted results are found to be closer to the experimental values with a maximum fraction of absolute variance, minimum root-mean-square errors and minimum coefficient of variance. The results showed that the pin–fin absorber plate packed with paraffin wax has additional heat storage for the period of 3 h with 2–5 °C enhanced outlet air temperature when compared to the flat absorber plate. The FCSAH using pin–fin absorber plate packed with paraffin wax has 3–35 % higher thermo-hydraulic efficiency with 2–15 % higher exergy efficiency when compared to the flat absorber plate. The results confirmed that pin–fin absorber plate packed with paraffin is a good option to enhance the thermodynamic performance of a FCSAH.